Re: JIT interface slowness

[Pedro Alves <pedro@codesourcery.com>]

On Friday 31 December 2010 23:11:55, Vyacheslav Egorov wrote:
> > If your JIT runs on a separate thread, and pausing just that
> > thread doesn't block all others immediately, you could try
> > running gdb in non-stop mode.
> >
> 
> I thought you said that hitting __jit_debug_register_code stops the
> world i.e. stops all threads. 

I did, and it does, in all-stop mode, which is the gdb default
mode.  There's a new-ish mode (called the non-stop mode), where
gdb does _not_ stop all your threads whenever a breakpoint is
hit --- only the particular thread that hit the breakpoint.
(There's a chapter about it in the manual).  Not all your users
will want to enable this mode.  And most frontends don't know
about it either, so, it's not really a "fix" for everyone, I
guess.

> > What was the cost for a first registrations?
> 
> Up to 88 it is < 2ms
> Up to 276 --- < 10ms
> Up to 535 --- < 50ms

> registered new entry, total 1115 entries [took 333 ms]
> registered new entry, total 1116 entries [took 334 ms]
> registered new entry, total 1117 entries [took 335 ms]
> registered new entry, total 1118 entries [took 336 ms]

It would be quite interesting to know what causes this.
You should also try a recent snapshot (or cvs head), and
7.2, if you aren't already.

-- 
Pedro Alves